United States Department of Transportation
i
First flush reactor for stormwater treatment for elevated linear transportation projects.
-
2009-06-01
[PDF-631.69 KB]
Details:
-
Creators:
-
Corporate Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
Edition:Final report; Dec. 2007-May 2009.
-
Corporate Publisher:
-
Abstract:The United States EPA (Environmental Protection Agency) MS4 (Municipal Separate Storm Water Sewer System) Program regulations
require municipalities and government agencies including the Louisiana Department of Transportation and Development (LADOTD) to
develop and implement stormwater best management practices (BMPs) for linear transportation systems to reduce the discharge of
various pollutants, thereby protecting water quality. An efficient and cost-effective stormwater BMP is urgently needed for elevated
linear transportation projects to comply with MS4 regulations. This report documents the development of a first flush-based stormwater
treatment device, the first flush reactor, for use on elevated linear transportation projects/roadways for complying with MS4 regulations.
A series of stormwater samples were collected from the I-10 elevated roadway section over City Park Lake in urban Baton Rouge.
Stormwater treatment experiments were conducted using three laboratory columns filled with different combinations of filter medium
layers. In terms of contaminant removal efficiency, the optimum filter medium combination was found to be (a) a mixture of Smart
Sponge and Hydra CX2 in the top layer, (b) zerolite in the next layer, (c) sand, (d) sawdust, and (e) gravel in the bottom layer. Results of
the laboratory experiments indicate that the first flush reactor with the optimized filter medium layers is able to remove over 85% of total
suspended solids (TSS), 90% of total phosphorus, 99% of NO2-N and NO3-N, and 70% - 90% of fecal coliform bacteria. Tested heavy
metals include Al, As, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Na, Ni, P, Pb, Si, and Zn. In general, removal rates of heavy metals through the
recommended filter media are higher than 80%. The removal rates of three toxic heavy metals including cadmium (Cd), copper (Cu), and
lead (Pb) are higher than 90%. Hydrocarbon levels in the stormwater samples were too low to be detected. Some unsolved problems in
the current design of the first flush reactor include the low removal rate (15%-58%) of TKN (Total Kjeldahl Nitrogen) and the slight
release (up to 20%) of toxic metal zinc (Zn) from the reactor. The problems may be resolved by conducting more column tests and
possibly replacing the Hydra CX2 with other types of fiber mulch. Experimental results presented in this report may be used for further
study of filter medium selection and for optimization of the first flush reactor.
Guidelines for design, field construction, operation, and maintenance of the first flush reactor are provided in this report to help
environmental engineers and stormwater managers design and operate the first flush reactor properly and achieve the stormwater
pollutant removal efficiency required in the MS4 program.
-
Format:
-
Funding:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type:
